The present invention relates to forming holes in a substrate. In particular, the present invention relates to mechanically punching holes in films, especially thin films for use in the electronics industry. More particularly, the present invention relates to a method and apparatus for ensuring hole quality and minimizing or eliminating damage to the films during the hole punching process.
Some aspects of the fabrication of structures for use in the electronics industry require the formation of holes in a substrate. One method for forming such holes is to physically punch the holes in the substrate. Typically, the substrates are thin films.
Frequently, the punching of holes occurs while the punching device and the substrate move relative to each other. The movement of the punching device and the substrate may take place in both the X and Y directions. That is, movement may take place parallel to the plane of the substrate. Such movements along the axial directions are referred to as xe2x80x9cpunch-on-the-fly Xxe2x80x9d (POFX) and xe2x80x9cpunch-on-the-fly Yxe2x80x9d (POFY).
During both POFX and POFY operations, there is at least some lateral component of movement of the punch and/or the substrate, or film or web, relative to each other while the punch is actually within the substrate, during the punch xe2x80x9cin web timexe2x80x9d. This time interval is referred to as the web engagement time and refers to the interval during which the punch is mechanically engaged with the hole. The magnitude of the relative motion of the punching device and the substrate during this interval is dependent upon the velocity of the relative movements.
As a punch is used to produce holes in a substrate, it generates fine particles, much as a saw blade generates dust. These fine particles gather on the punch and punch guides, causing frictional drag on the movement of the punch. This problem is particularly important with punches that have slow actuation cycles. The debris can cause the actuation cycles to slow.
Clogging of punch guides, causing frictional drag on the movement of the punch, is also a particularly potentially damaging problem with POFX and POFY systems. For example, as the punch movement is delayed, the substrate and punch assembly continue to move relative to each other. This initially may cause only hole quality problems. However, as time goes on, the delayed punch movement can rip the substrate. Ripping of a substrate may necessitate discarding the entire substrate, or web or film. This can be a particularly costly problem, especially when ripping occurs near the end of a long web or film structure, but still results in discarding the entire web or film.
The frictional drag caused by a buildup of substrate material in the punch assembly can delay the initial stroke of the punch. The frictional drag may also delay the return stroke of the punch. In the most severe cases, the frictional drag on the movement of the punch may cause a failure of the punch to return at all.
Slowing of the punch cycle may also be caused by other conditions, such as punch and die edge wear. These wear conditions also increase the energy required to pierce the film, thus slowing the punch and decreasing the rebound velocity.
In view of the above, it is apparent that problems caused by punch slowdown, regardless of the cause, are costly problems.
Accordingly, one object of the present invention is to provide a method for detecting delays in the punch actuation process.
An advantage of the present invention is to stop punch firing if a delay in the punch actuation process is detected.
It follows that another advantage of the present invention is to help prevent damage to substrates being punched.
An additional object of the present invention is to mechanically decouple the punches vibrationally so as to permit isolated detection of punch movements.
In accordance with these and other objects and advantages, aspects of the present invention provide a method for minimizing transmission of vibrations among punch actuators for punching holes in a substrate. The method includes the step of decoupling mechanical vibrations between the punch actuators.
According to other aspects, the present invention provides an apparatus for mechanically forming holes in a substrate. The apparatus includes a plurality of punches for engaging the substrate and forming holes in the substrate. A plurality of punch actuators actuate the punches. The apparatus also includes means for vibrationally decoupling the punch actuators.
Additionally, aspects of the present invention provide a method for preventing mis-punching of holes in a substrate. The method includes sensing parameters related to the timing of movement of punches during a plurality of punching operations. A change in the parameters over time is detected. The change in the parameter values is compared to a predetermined value. The punching of holes is ceased when the detected change substantially differs from a predetermined value by a predetermined amount. Alternatively, the energy of the punch actuation may be increased to overcome the energy losses and reduce the measured delays.
The present invention also provides methods for preventing damage to the substrate during the punching of holes in the substrate, an apparatus for preventing mis-punching of holes in a substrate, and an apparatus for preventing damage to a substrate during punching of holes in the substrate.
Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.